To copy filesto a second medium(a diskor tape) as a precaution in case the first medium fails. One of the cardinal rules in using computers is back up your files regularly.
Even the most reliable computer is apt to break down eventually. Many professionals recommend that you make two, or even three, backups of all your files. To be especially safe, you should keep one backup in a different location from the others.
You can back up files using operating system commands, or you can buy a special-purpose backup utility. Backup programs often compress the data so that backups require fewer disks.
Examples of second medium that can be used to back-up files.
To copy filesto a second medium(a diskor tape) as a precaution in case the first medium fails. One of the cardinal rules in using computers is back up your files regularly.
Even the most reliable computer is apt to break down eventually. Many professionals recommend that you make two, or even three, backups of all your files. To be especially safe, you should keep one backup in a different location from the others.
You can back up files using operating system commands, or you can buy a special-purpose backup utility. Backup programs often compress the data so that backups require fewer disks.
Examples of second medium that can be used to back-up files.
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Source: http://www.webopedia.com/TERM/b/backup.html